One in four people does not trust the police, according to a new poll.

A ComRes survey for the Sunday Mirror has revealed that 24% have lost faith following a series of high-profile scandals involving officers.

The research also revealed widespread concern that punishments for criminals are too lenient, with more than three-quarters (78%) believing that people convicted of crimes are not punished enough.

Around half (51%) think drugs are the largest cause of crime, followed by bad parenting at 29% and soft punishments at 25%, according to the survey.

The vast majority of people (86%) think having more officers on the beat is an "effective" way of tackling crime, while more 72% believe longer prison sentences would help stamp out crime.

But there is some good news for police forces, as 90% of those quizzed said they feel safe in their local neighbourhoods.

The findings come ahead of the publication today of the Sunday Mirror's Justice On Trial supplement, an 24-page investigation into crime, the prison system and reoffending.

Writing in the newspaper, former Labour home secretary David Blunkett, who announced yesterday that he will stand down from Parliament at the next election, warned that prisons act as "colleges of crimes", fuelling criminal behaviour.

Mr Blunkett said: "When there is a continuing problem with a youngster there will be something behind it, major emotional or massive problems in parenting or going off the rails.

"At that point you stand a chance about doing something about it. That's the first thing. I'm in favour of a two-handed approach.

"Be really tough to send the right signals on terrible crimes such as murder, rape and physical abuse. And we should have tough community sentences at the other end of the scale so we keep as many people committing lower levels of crime out of prisons, which act as colleges of crime.

"Youngsters go in and often come out worse."

Commenting on the results of the poll, Adam Pemberton, assistant chief executive of charity Victim Support said: "It is worrying that nearly one in four people do not appear to trust the police. They will be less likely to report crimes and access the support they need.

"And if people do not trust the police they are less likely to appear as a witness and support prosecutions."

Pete Saunders, of the National Association of People Abused in Childhood, said: "Many of the thousands of people I have dealt with have had a negative experience of the police - it's the bad ones you remember."

The survey, which questioned 2,032 British adults online, comes in the wake of a series of scandals which have involved police officers in recent years.

Four officers have been sacked over the Andrew Mitchell "Plebgate" row, which erupted after an altercation between the former Government chief whip and officers when he was refused permission to cycle through the main Downing Street gate in September 2012.

Pc Toby Rowland , who was manning the gate, claimed Mr Mitchell used the words ''You should know your f****** place, you don't run this f****** Government, you're f****** plebs'' after he was refused permission to cycle out.

However, the MP insists he said: ''I thought you guys were supposed to f****** help us.''